Counterbore.



" nnitrnn sTArras P TEntr OFFICE.

JOHN 1?. LE BARON, OF BIDGWAY PENNSYLVANIA, ASSIGNOB 0F ONE-HALF TO I CLIFFORD S. ESTES, OF RIDGWAY,'PENNSYLVANIA.

COUNTERBORE.

Specification of Letters Patent.

Application filed November 6, 1909. Serial No. 526,545.

Patented Aug. 16,1910.

To all whom it mag concern:

Be it known that I, J 01m F. LE BARON, a citizen of the United States, and a resident of Ridgway, in the county of Elk and State of Pennsylvania, have invented a new and Improved Counterbore, of which the following is a full, clear, and exact descrlptlon.

Among the principal objects which the present invention has in view are: .to proretaining the pilot and cutting tool in the tool holder, said means being removed from contact with the wall of the hole being bored; and to provide a counter-bore and tool holder therefor simple, economical and durable in construction.

One embodiment of the present invention is disclosed in the structure illustrated in the accompanying drawings, in which like characters of reference denote corresponding parts in all the views, and in which- Figure 1 is a side view of a tool holder with a pilot and cutter constructed and equipped in accordance with the present in vention; Fig. 2 is a partial longitudinal section thereof, showing the pilot and cutter inside elevation; Fig. 3 is a partial longitudinal section of the tool, holder, pilot and cutter, and means for holding the same; Fig. 4 is a perspective view of a counterbore cutting tool constructed in accordance with the present invention; and Fig. 5 is a perspective view of a pilot constructed 1n accordance with the present invention.

A tool holder 7 is provided with a tapered shank 8 of usual construction, and a centrally bored hole 9 opening into the tool holder 7 from the forward end thereof. A

transverse slot is milled across the end of the tool holder 7 concentrically with the hole 9, and of a width adapted to receive a cutter 10.

r In operation, the pressure is introduced upon the cutter in a constant rotary direction, the effect of which is to rotate the cutter within the said slot until the sides of the cutter rest upon the opposite edges of the said slot. The cutters are placed in a'slot 11 provided in a pilot 12: The pilot 12 is cylindrical, and at the forward end is formed solidly, as illustrated in Fig. 5 of the drawings. The slot 11 is formed to hold cutters of a given thickness, which will snugly fit the. said slot and prevent the contraction vlde a pilot to hold the cuttin tool by he ing clamped thereon; to provi e means for of the sides of the pilot at that point. All pilots used in the holders 7 are fitted neatly to the hole 9, therefore when a cutter is placed in the slot 11 and the slotted end of the pilot forced into'the said hole, the barrel of the said pilot is firmly held, and is thereby held in the center wlth the tool .7. The cutters 10 are provided with an extension 13, adapted to extend within the continuous cyllndrical portion of the hole 9 above the transverse slot formed in the holder. The extension 13 is preferably formed to neatly fit the hole 9, thereby centering the lateral extensions of the cutter when placed in operative position. The side of the pilot 12 1s cut away to form a flat rest 14: for a set screw 15, whereby the pilot 12 is held in the hole 9. The set screw 15 is suitably threaded, and 1s mounted in a tapped perforation formed in the side of the holder 7. The set screw 15 is provided, in the present instance, with a hexagonal recess 16 to receive a solid hexagonal headed wrench. When the screw 15 is driven home, the upper edge thereof is not extended beyond the surface of the holder 7 The operation of the device is obvious. The advantages in its use are equally obvious, numbering among which may be mentioned the rapidity and ease with which the cutters may be removed from and inserted in the tool holder 7; the avoidance of chatter in the tool; and the ease and economy invollved 1n replacing a worn out or damaged p1 0t.

I Havlng thus descrlbed my invention, what I claim as new and desire to secure by Let- 4 ters Patent is 1. A counter-bore comprising a cylindrical pilot having a transverse slot formed therein; a cutting tool adapted to fit within said slot in said pilot; a holder having a round hole in the forward end thereof; and a device carried by said holder for holding said pilot in said hole by frictional engagement with the said pilot.

2. A counter-bore comprising a cylindrical pilot having a transverse slot formed therein; a holder havin a hole formed in the forward end thereo adapted to receive the slotted end of said pilot; a cutting tool adapted to fit within said slot in said pilot;

and a device carried by said holder for holding said pilot in said hole by frictional engagement with the said pilot.

3. A counter-bore comprising a cylindrical pilot having a; transverse sot formed therein; a holder for said pilot; a cutting tool adapted to rest within the slot forme 5 in said pilot and having an extension centrally located and'adapted to fit within the said holder; and a device carried by said holder for holding said pilot therein by frictional engagement with the said pilot.

4. A' counter-bore comprising drical pilot having a transverse slot formed therein, and a flattened surface formed on one of the portions of said pilot separated by said slot; a cutting tool adapted to rest 15 within the slot formed in said p' 0t and hava cylin- I with JOHN F. LE BARON.

Witnesses:

G. T. GREINER, EMMA Lucas. 

